A hollow or transverse-hollow cast sleeper of this type has been disclosed in DE 43 15 200 [U.S. Pat. No. 5,562,267]. Hollow cast sleepers are employed in railroad track systems, in particular, to accommodate the switch actuator (closure-type hollow cast sleeper) or for cable crossings (cable-type hollow cast sleepers), and are installed at the same site as existing concrete, wood, or steel ties, or as replacements for these ties.
Known hollow cast sleepers or box-type hollow cast sleepers in the form of close cast sleepers are preferably fabricated from folded sheet steel bent into as U-sections, or mace by casting, and ensure that the hollow cast sleeper sections can be tamped in as well as the adjacent concrete, wooden, or steel ties.
However, in order to achieve the same or improved stable positioning—by which is meant the elasticity in the tie bedding as well as the smallest possible transverse and longitudinal displacement of the hollow cast sleeper—as is obtained with the corresponding, for example, replaced concreted, wooden, or steel sleeper, it is often necessary to level the contact area between the lower floor surface or the so-called footing of the hollow cast sleeper and the ballast of the track section. As a rule, this leveling or fitting is effected only with standard concrete sleepers by means of elastic or semi-elastic footings for the lower floor surface.
In the case of concrete sleepers, the sleeper footings in the form of bearing plates are generally attached by adhesive, or, for example, cast on as an integral component.
Due to the operational load on standard sleepers and due to the tamping of adjacent hollow cast sleepers with ballast, the circumferential edge zone of the attached elastic bearing plate tends to peal off or tear off, this last effect being caused by transverse and longitudinal movements of the sleeper in the ballast bed.
The entire surface of the bearing plates is attached to the lower face of the sleeper or to the lower sleeper floor. The plates are thus generally fabricated in one-piece form in a size corresponding to the entire surface of the lower face of the sleeper, a procedure that results in additional costs in the fabrication process.
Since generally only one continuous bearing plate or sleeper footing is used per standard sleeper, it is possible only to a limited degree to achieve a balanced distribution of elasticity. Nevertheless, sleeper footings are provided since without such a bearing plate the sleepers would provide even less stable positioning in the ballast bed or laying below grade.